The challenge of talking about “The Disaster Artist” is that it’s funnier more often and in more different ways than there are synonyms for hilarious, and that’s even if you want to resort to words like “risible” and “knee-slapping.” This movie is seriously funny, surprisingly funny, not funny in a way that you ever decide to laugh, but funny like you couldn’t keep quiet even if you wanted to. The laughs, as they say, keep coming.

The comedy, directed by James Franco, is all about the making of a movie. Though appreciating “The Disaster Artist” hardly depends on this fact, this is actually a true story, about the making of “The Room” (2003), which has apparently gone down in history as one of the most amazingly bad, entertainingly awful films ever made. But — this is important — you do not need to see “The Room” before seeing “The Disaster Artist.” In fact, it would probably be better — more preserving of the freshness of the experience — to see “The Disaster Artist” first.

Indeed, if you didn’t know “The Room” existed, you would just assume “The Disaster Artist” to be fiction, not only because the story is so bizarre, but because the treatment of the main character, Tommy Wiseau (played by James Franco), is so unsparing. Rarely, if ever, has a living person been portrayed with such hysterically funny disrespect.

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Based on the book by Greg Sestero and Tom Bessell — “The Disaster Artist: My Life Inside ‘The Room,’ the Greatest Bad Movie Ever Made” — the movie begins in San Francisco, with Greg (Dave Franco) and Tommy meeting in an acting class at the Shelton Studios on Sutter Street. Greg is too inhibited to be a good actor, and so he is impressed by Tommy, who performs the “Stella” scene from “A Streetcar Named Desire” by rolling on the floor and climbing the scenery.

They’re both awful actors — Greg in a curable, normal way, and Tommy in a flashy, permanent way that the world had not yet seen. If originality, even in awfulness, is a form of talent, Tommy has definitely got something.

Before we go any further, something must be said about James Franco as Tommy. He goes through the movie in a state of dreamy self-absorption, talking in a strange Eastern Europe accent (even though the character claims to be from New Orleans). The accent, which is weird enough to get a potential laugh out of almost every line, turns out to be a pretty dead-on copy of Wiseau’s actual accent. But Franco does more than an imitation. He climbs into the head of this character and gives us his thought processes, which are ultimately an even greater source of jaw-dropping comic amazement.

For a time, Greg is happy to have an older artistic mentor, and Tommy is just happy to have someone, anyone, who looks up to him. They move together to Los Angeles, where they become roommates, and Greg begins to realize that somehow, mysteriously, Tommy has money. After being humiliated by a Hollywood producer who tells him he has no talent (Judd Apatow in a humorous cameo), Tommy decides to write, direct and star in his own movie.

“The Disaster Artist” is funny from the beginning, but it becomes downright side-splitting once Tommy gets onto a film set. As everyone knows, this process surprisingly ends up with an actual artifact, a real-life movie. The scene of the movie’s premiere — an extended scene that unfolds slowly — is among the funniest theatrical disasters ever put on celluloid, as uproarious and diverting (and as knee-slapping and risible) as the one in Buster Keaton’s “Spite Marriage” from 1929.

In fact, the shelf life of that scene may end up being as long as the one in the Keaton film. It’s hard to imagine “The Disaster Artist” ever not being funny.